It didn't burn up, it broke up. There were quite a few papers, suitcases, etc recovered which are charred on the edges and intact otherwise. Quit it with the conspiracy hysteria. At least they're talking about it now, rather than hushing it all up as they did with Challenger.
Everyone knows, NASA has known for a long time, the shuttle is always within a few percent of disaster. Management tries to downplay the risks, provokes complacency. For the money we spend, these guys need to be going the extra mile on disaster insurance. If they didn't, heads should roll. But even if they do everything right, it can still catch up to them. Remember all the fires, blackouts, computer failure, collision etc happening on Mir? Those guys dodged a thousand bullets.
That's life on the frontier.
I have yet to see any plausible excuse for adding the added weight of the new Space Hab 2 lab. None of the experiments conducted sound as if they were that vital.
The really great one on MIR was the oxygen generator the fired off. That's the thing that brought down the Valuejet. In space no less. And they survived.